Melissa Phillips and her partner, Jordain Palmer, could not cope with children, his lawyer told the court. Photograph: Linda Nylind for the Guardian

A mother and her partner are starting custodial sentences for a catalogue of abuse that left a 14-month-old girl covered in injuries, with every fingernail blackened and bruised.

The little girl was found with bruises all over her face, ears, torso and legs and fractures to her hands, left wrist and right shin bone.

All 10 fingernails on her hands and her big toes were torn and black, either from being stamped on or shut in a doorframe.

Melissa Phillips, 19, was sentenced to four years after admitting cruelty to a child under 16.

Her partner, Jordain Palmer, also 19, was found guilty of the same offence for failing to stop the abuse and also sentenced to four years.

Judge David Ticehurst, sentencing Palmer at Bristol crown court, told him that if he had the power to stop him ever having children, he would do.

He told the sobbing defendant: "It is a matter of regret that I do not have the power to stop you having children in the future.

"If I had the power to, I would use it. You are not a fit and proper person to have children. There was a systematic course of deliberate cruelty to her.

"Despite that, you did nothing whatsoever about it and you let matters continue. You were not responsible for the injuries but your culpability is almost as great as [Phillips's]."

Concern was raised about the frail state of the girl in March last year. The toddler was just 14 months old when a worried relative took her to a GP.

A doctor immediately referred her to Bristol children's hospital after noticing her walk with a limp and staff there concluded the injuries were not accidental.

Phillips was sentenced to four years in a young offenders' institution last week after admitting child cruelty. Palmer was found guilty of the same offence following a trial at Bristol crown court and was sentenced on Tuesday.

Kerry Barker, prosecuting, said injuries to the girl's nails could have been caused by her fingers being trapped in a door or stamped on. Injury to her ears could have been caused by being picked up by them.

Fiona Elder, defending Palmer, said the pair could not cope with children. Elder added: "They have an inability to cope with young children and the stresses and strains of life in general."

Outside court Detective Constable Patrick Schofield, from Avon and Somerset police, said: "The long custodial sentences are welcomed by us, and also the assistance of other agencies such as social services, doctors and medical staff."